Henry Small and Eugene Garfield have contributed’ an
interesting suggestion
for using co-citation analysis to explore multiple-link indirect paths
that might connect two literatures.

They also note that, in my
article,
I had failed to find citation and indexing analysis useful in revealing
logical connections [1].
However, in the light of my subsequent Brief Communication concerning
an
exploratory trial-and-error search strategy, that failure itself can
now
be placed in a new and more positive perspective [2].
Once a logical connection between two literatures is hypothesized
(perhaps
with the aidof the idea proposed by Small and Garfield), it is
still
necessary to determine whether that hypothesis is already known, our
goal
being to find previously undiscovered connections. A co-citation
analysis
of the two literatures is then helpful. If there are many co-citations,
the hypothesis can be discarded for our purposes on the ground that
other
people have already brought the two literatures together (by cociting
them)
and therefore almost certainly must have noted the connection. A
negative
result (i.e., few or no co-citations) is even more interesting for it
suggests
that the hypothesis has not’ before been proposed, and so is eligible
for
further study. Thus what I called a "paradoxical quest for the absence
of retrieval clues" [1, p. 233], was neither as whimsical nor as
paradoxical
as it might have seemed. The route to successful hypotheses is first to
make a lot of guesses — then get rid of
those
that are wrong.

Don R. SwansonUniversity of Chicago

1. back to textSwanson, Don R. "Two Medical Literatures that are
Logically
but not Bibliographically Connected." Journal of the American
Society
for Infor~nation Science. 38(4):228—233; 1987.